Causes of increased intracranial pressure can be classified by the mechanism in which ICP is increased:
mass effect such as brain tumor, infarction with oedema, contusions, subdural or epidural hematoma, or abscess all tend to deform the adjacent brain.
generalized brain swelling can occur in ischemic-anoxia states, acute liver failure, hypertensive encephalopathy, pseudotumor cerebri, hypercarbia, and Reye hepatocerebral syndrome. These conditions tend to decrease the cerebral perfusion pressure but with minimal tissue shifts.
increase in venous pressure can be due to venous sinus thrombosis, heart failure, or obstruction of superior mediastinal or jugular veins.
obstruction to CSF flow and/or absorption can occur in hydrocephalus (blockage in ventricles or subarachnoid space at base of brain, e.g., by Arnold-Chiari malformation), extensive meningeal disease (e.g., infectious, carcinomatous, granulomatous, or hemorrhagic), or obstruction in cerebral convexities and superior sagittal sinus (decreased absorption).
Elevation in ICP can be graded as follows: Normal ICP 0 - 15mm Hg Mile elevation 16 - 20 mm Hg Moderate elevation 21 - 30 mm Hg Sever elevation 31 - 40 mm Hg Very severe elevation 41 mm Hg and above SIGNS AND SYMPTOMS
decreased level of consciousness, confusion, restlessness, lethargy, difficulty with memory and thinking
MOA: reduces the water content of the brain due to the establishment of an osmotic gradient between the brain and the intravascular compartment. Mannitol is a large molecule and will not cross the BBB.
b. Dosage: 50 – 200 Gm (1 Gm/kg) IV over 24 hours
Titrated to maintain urine output at 30 – 50cc/hr.
Patients with anuria related to renal disease, pulmonary edema, severe dehydration, or active intracranial bleeding.